target to determine is earning value of day 1
each day Dan earns $10 more than other day
so day 1 = x
day 2 = x+10
day 3 = x+30
so on till day 15 ; x+140
#1
His total earnings for the three most recent work days equal $690.
recent three days ; day 13,14,15 ; and day 14 value would be mean of 690 ; 690/3 ; $330
so day x+130=330
x= $200
sufficient
#2
His total earnings for the three most recent work days exceed his total earnings for the first three work days by $360
three most recent days salary
3x+ ( 120+130+140) ; 3x+ 390
and salary of first 3 days ; 3x+(10+20) ; 3x+30
we are given
3x+390=3x+30+360
value of x cannot be determined
insufficient
IMO A
Bunuel
Each day at Dan’s new job, he earns $10 more than the day before. If he just completed his 15th day of work, how much did he earn on his first day?
(1) His total earnings for the three most recent work days equal $690.
(2) His total earnings for the three most recent work days exceed his total earnings for the first three work days by $360
Are You Up For the Challenge: 700 Level Questions